There are three constituents and interrelated aspects of wastewater management
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- Collection
- Disposal \ re-use
- Treatment
Collection
Collection of domestic and industrial wastewater is best achieved by fully developed sewerage or water carriage system. The planning and design of wastewater collection facilities involve the determination of wastewater flow rates: the hydraulic design of sewers, large conduits, and junction and diversion structures. The selection o sewer achieved and pumping station most sewers are repaired have to be made. Sewers are commonly laid straight lines, manholes are being provided at all changes of direction, gradient and diameter. With the modern developments in other fields, many recent changes have been made in wastewater collection-notable amongst them being photo grammatical and computer techniques to the design sewers, the improvement at contraction materials, and the application at computers in the control at storm sewers.
Treatment
Treatment of waste is essential in order to reduce the spread of communicable diseases caused by the pathogenic organisms in the sea age and to prevent the pollution of surface and groundwater. The treatment of wastewater is carried out by a combination of physical unit operations and chemical and biological unit processes before the end product can be safely disposed of. The form of treatment normally adopted consists of providing an environment in which natural processes of decay can be intensified and controlled so as to take place in the least objectionable manner.
Disposal
After the treatment, the problems of disposal arises. The most important recent trend in the field disposal is the establishment at increasingly stringent requirement to protect the environment.
Currently used different disposal methods are
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- Dilution in streams and rivers
- Land application
- Re-use in aquaculture and crop irrigation
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The sludge and concentrated pollutants are disposed of in lagoons sludge drying beds are sanitary landfills for small treatment plants and vacuum filtration followed by heat drying and incineration in large treatment plants.